The loss of the tags from livestock is a common problem. When animal tags are lost the history, genetic recordings, and other data like veterinary related records is lost as well. Several methods are commonly adopted to increase tag retention. Animal tags are made of heat-seal layered thermoplastics, of size and weigh to provide resilience in difficult everyday animal conditions.
An example of the prior art technique is found in U.S. Pat. No. 5,725,261 to Rahn disclosing a continuous roll lamination process of plastic substrates under heat and pressure at a temperature and pressure sufficient to cause the plastic material to penetrate the interstices of the substrate and form a unitary resilient plastic structure. The lamination station typically applies about 270-330° F.
The technique was improved in U.S. Pat. No. 6,758,000 to Sandt et al disclosing livestock identification tag assembly comprising: a heat seal laminate comprising: (i) a facestock having an upper surface and a lower surface; (ii) a heat-activatable adhesive layer having an upper surface and a lower surface, wherein the upper surface of the heat-activatable adhesion layer is adhered to the lower surface of said facestock; (iii) an ink or graphics layer adhered to the lower surface of said heat-activatable layer; and (b) a flexible polymeric substrate; wherein the lower surface of the heat-activatable adhesive of the laminate is adhered to the substrate. In one embodiment, the ink or graphics layer is positioned between said heat-activatable adhesive layer and said facestock.
Commonly used animal identification tags are described and covered by such U.S. Pat. Nos. 4,920,671, 5,152,249, 5,429,393, 5,725,261, 6,613,179, 6,758,000, WO2007/095684, 8,573,502, many of them marketed commercially in the United States.
WO/2009/089215 discloses an animal tag and methods for making an animal tag include a primary body of material (e.g., that includes a circuit holding portion and an animal attachment portion), a circuit assembly, and a cover configured to cover the circuit assembly. The cover is welded to the primary body of material using light radiation.
The prior art animal tags employ thermoplastic welding utilizing, inter alia, heat or radiation in combination pressure to melt the tag layers so as to fuse and heat-seal the thermoplastic layers. To that end, the prior art employs heat activated adhesives. Needless to say, application of heat/radiation complicates the manufacturing process resulting with increased cost.
Another disadvantage of the prior art tags stems from the damage which inevitably occurs to electronic components found in proximity to the increased heat.
In addition, application of heat reduces the scope of materials which can be employed forcing the engineering of animal tags to utilize generally softer thermoplastic with increased thickness, use laser welding, use embedded melting flux cores and plastic molding.